Currently there are known combination weighing machines comprising two parallel chain drives between which carriages are arranged, joined to the chains so that the coordinated motion of these in the same direction makes the carriages move along a closed path in which, conventionally, a horizontal straight upper feed section, a lower horizontal straight return section and certain curved sections are distinguished. Buckets are attached to these carriages, and the machines comprise a plurality of work stations distributed along the trajectory of the carriages, and by extension along the path of the buckets attached to the carriages, such as a loading station where fruit is fed into the buckets; a weighing station where the fruit contained in each bucket is weighed; and an emptying or unloading station where the buckets are emptied.
In so-called combination weighing machines, several buckets are attached to the same carriage, each carriage defining a row of buckets, and at the emptying station there is a selective emptying of those buckets, attached to the same carriage or to different carriages, whose total fruit weight is closest to a predetermined value.
Generally, the buckets are in the shape of a tub with an opening at the top for receiving fruit from the loading station, the buckets of the same row being connected to the carriage capable of rotating over a crossbar of the carriage itself.
The tilting buckets remain fastened in horizontal position throughout the entire path by means of a tilting locking lever, which is capable of being moved by an actuator element linked to the unloading station in order to carry out the dumping of the bucket.
The tilting lever with rotation capacity is mounted on a fixed point of the bucket and is in turn interconnected to the carriage by means of a tensioning spring which tends to keep said lever in a locking position, in which it remains fixed by fitting in a supportive rod of the bucket.
For unloading, as the bucket moves along its path, the corresponding actuator element contacts the upper end of the lever causing it to tilt until it disengages from the fitting stem, which in turn causes the bucket to dump and empty by gravity.
To return the bucket to horizontal position after unloading, the machine comprises a guiding ramp, located at the end of the path of the unloading station, which generates the reverse rotation of the corresponding bucket, which is then locked again by means of the tilting lever.
The machine also includes means of control that, based on data received from the weighing station and by using the appropriate software, select the combination of buckets of the same or different rows whose sum of weights is close to the predetermined weight for packaging, and sends an activation command to the actuator elements, for example movable stops, intended for swinging the respective tilting levers of those buckets that have been selected to dump, with the subsequent unloading of the fruit as it passes over the unloading station.
An example of a weighing machine of the type described above is found in patent document ES 2153749 B1.
Another example of weighing machine that also uses tilting buckets that unload by dumping is described in the patent ES 2117563 B1.
This type of tilting buckets that unload by dumping require structurally complex mechanisms in order to achieve adequate bucket motion from the horizontal locked position to the dumping position and vice versa, so they generally require a large amount of moving parts that increase manufacturing as well as maintenance costs.
It would be desirable to have a bucket that could be coupled to dynamic weighing machines, ensuring quick and easy unloading of the product contained therein over the unloading station, and that would also have a simpler and more compact structural configuration allowing for appropriate integration in the machine, and also ensuring minimal wear of its moving parts.
In other applications, there are also known buckets that include a collapsible bottom lid that, once a retention mechanism is actuated for its opening, can tilt freely through the effects of gravity allowing the emptying of the products they contain.
The nature of the products that are usually transported by buckets in a weighing machine of the type described above, such as oranges, tangerines, apples, etc., cause that this type of buckets becomes inoperative due to a disadvantage, namely, on occasions the products become trapped inside the bucket walls because of friction, and therefore cannot achieve a correct emptying or they may even fail to unload any of the product even when the bottom lid tilts freely to opening position through the effects of gravity.
In this case, it would be desirable to have a solution especially suitable for dynamic weighing machines of the type that weigh fruit and vegetables, which would ensure a proper unloading of all the products contained in the buckets of the machine during the unloading operation.